Contactless thermal protector.



F. B. 000K. GONTAGTLRSS THERMAL PROTECTOR.

APPLICATION FILED APR. 12. 1907. 4 903,818. Patented Nov. 10, 1908.

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UNITED STATES PATENT orricii.

FRANK B. COOK, OF CHICAGO, ILLINOIS.

VCObT'IAC'lLESS THERMAL PROTECTOR.

- Specication of Letters Patent.

Patented Nov. 10, 1908,

Original application filed *.Tuly 28, 1905, Serial No. 271,662. Divided and this application led April 12, 1907. Serial No. 367,859.

To all whom it may concern:

Be it known that I, FRANK B. .Oooin a citizen of the United States of America, and a resident of the city' of Chicago, in the State of Illinois, have invented a new and useful Contactless" Thermal Protector, (Case No. 132,)'of which the followingis a specifica! tion,v reference being had to the accompanying sheet of drawings, illustrating saine.v

This invention is an improvement on my United Staates Letters Patent No.V 785,707, issued March 28, 1905, for thermal cut-out for electrical circuits, and a division of my application for Letters Patent of the United States, Serial No. 271,662, iiled July 28,1905.

My invention relates to electrothermal protectors such as are used for protecting electrical circuits and apparatus from abnormal electric currents. I

to provide an electrothermal protector in which there are no loose contacts in the circuit, that is, a protector in which all of the contacts, either in the'protector or between the latter and its mounting and operating members, are normally soldered; and to provide lefficiency and simplicity of construction in such a protector.

Heretofore, it has been the practice to provide'a heat coil or thermal protector which is removably mounted in thecircuit which it is to protect, so`that the contacts with the protector are merely pressure contacts. With this form of protector,corrosion of the pressure contacts, or dust, dirt 0r the' like, therein, may produce an open circuit or ygive a contact of very high resistance.

In this presen-t invention it is my intention to provide a protector in which there are no pressure contacts, and thus do away with the objectionable features of the latter. Consequently I provide a protector in which all of the contacts in the protector or between the latter and its coperating members, are soldered. When -the protector operates, certain soldered parts" separate and thus open' the circuit through the device.

I'will more particularly describe my invention by reference to the accompanying drawings, in which,- Figure l, is a side elevation' of the protector of the invention, vwith portions shown in cross-section; and Fig. 2 is a similar view of a modified form of the invention.

` Like characters refer to like parts in the several figures.

B is preferably a piece of graphite or carbon, plated with -metal at its ends overthe portions 0 and aand turned away at 'my to adjust the resistance thereof to any desirable value. In making this element B the whole piece of resistance 'material may be electroplated all over, withcopper or any suitable metal, and the portion m turned down to remove the portion of the plating at fm, and adjust the resist/ance of B to the desired value. The plated end portions 0 and a of B are then soldered to the metallic members I] and Z by heat-susceptible material Ap, preferably a low-inelting-point metallic solder. The solder y), at n, may,vif desired. be a hard solder, as this joint in this construction of my invention is not-required to open when The principal objects of my invention are the device operates. y

An abnormally large current of electricity passing through Athe element B for a short length of time, heats same and thereby softens the solder 79 at 0 and allows the spring ineinber q to separate .from the element B and take the position Q3 of Fig. l. preferably against the ground plate r. This opera tion of the protector opens the circuit through saine and' preferably switches the objectionable current to earth.

Y The portion a of B is preferably enlarged to provide a suitable bearing surface to restagainst member Z. -Spring y is preferably formed into a-thimble at g., to provide a suitable surface to be soldered to the end portion 0 it is put under tension so as to operate to.

the position g3 when the solder p at 0 is softened. When the springv g is soldered to the portion 0, it is pressed to operative position without in any way putting the device or apparatus under binding or buckling stresses which are found in other forms of protectors when the apparatus is set, and which greatly reduce the efficiency of the operation of such devices.

` It Will be readily seen in my present in- Y vention, that when v'spring g operates it `the device operates and the latter' is not under unnecessarystresses While set.

In Fig. 2 I have shown a modified form of protector in which the heat-producing Winding ,m2 takes the place of the carbon or graphite rod B. A metallic plate n, is soll dered,y to the support Z, by solder p and is rigidly secured to spool m3 but insulated therefrom by an insulating disk n3. Winding m2 1s connected 1n circuit With spool m3'- andplate-ng. An insulating shell m, incloses theywinding mn The operation o'fthedevicc is similar'A to that of the device of Fig. 1. The insulating disk n, being placed between spool m, and plate n2,- conlinesthe greater part of the heat to the end o of vspool'mJ3 and hence thisend unsolders when the device operates, and the other end does not. Then again the heavy vpart l, conducts and radiates more heat from its solder joint p than spring g does from the solder joint' at 0, With' the same degree of heating, and this fact also tends to .keep the joint .between n, and Z2 from opening when the device operates.

If it is desired to open the circuit through -the protector for testing purposes the spring g may be unsoldered from the portion 0 in,-

, any suitable manner.

I donot Wish limit this invention to the particular -details l of construction herein shown, as many modifications may be made therein Without departing from the scope of the 'appended claims. Y

Vhat I claim as new and desire `tosecure by Letters Patent, is:

An electrothermal protector of the character described, comprising a heat cartridge, a metallic support for the cartridge to which the latter is soldered, an operable spring member having a thimble ther/ecn near one end thereof, a portion oit theflieat cartridge extending through the said thimble and being soldered therein with easily-fusible solder, the said soldered contacts eliminating all pressure contacts/from the circuit, an abnormally large current in the cartridge softening the said easily-fusible ysolder and releasing the said thimble and spring member from the cartridge, substantially as dcscribed.

2. In electrical Jrotective a Jaratus the l Pl a tension, the said soldered contacts eliminati ing all pressure contacts from the circuit, an abnormal current in the graphite softening the solder and thereby releasing the spring member and thimble from the graphite, substantially as described.

As inventor of `the foregoing I hereunto subscribe lmy name in the presence of tWo subscribing Witnesses, this 10th day of April, 1907. p

' FRANK B. COOK.

Witnesses:

FREDERICK R. PARKER, F. W. PARDEE. 

